As shown in FIG. 12 (Prior Art), a typical edge-perforated 35 mm filmstrip 10 has successive evenly-spaced film perforations 12a, 12b, 12c, etc. The pitch 14 of the film perforations 12a, 12b, 12c . . . from one perforation to the next perforation is uniform (the same) as indicated in FIG. 12, and as is commonly understood it is the distance between one point on a film perforation and a corresponding point on the next perforation.
A typical film-engaging sprocket drive includes a single sprocket wheel 16 having a series of eight successive uniform-pitch film-engaging teeth 18a, 18b, 18c, 18d, 18e, 18f, 18g, 18h that are similarly shaped to engage the filmstrip 12 within the film perforations 12a, 12b, 12c, etc. The teeth 18a, 18b, 18c, 18d, 18e, 18f, 18g, 18h are spaced 45.degree. apart, and the pitch 20 of the teeth is substantially the same as the pitch 14 of the film perforations 12a, 12b, 12c . . . to permit the teeth to enter the film perforations.